WO2023157831A1 - Bonding material composition, method for manufacturing bonding material composition, bonding film, method for manufacturing bonded body, and bonded body - Google Patents

Abstract

Provided are a bonding material composition whereby shear strength, heat resistance, electrical conductivity, and heat dissipation properties of a bonding layer can be enhanced, a method for manufacturing the bonding material composition, a bonding film, a method for manufacturing a bonded body, and a bonded body.　The bonding material composition pertaining to the present invention is characterized by including a flux and metal particles (P) including first metal particles (P1) and second metal particles (P2), the first metal particles (P1) being constituted from a core (C1) comprising Cu, and a Cu2O layer that covers the core (C1), and the second metal particles (P2) being constituted from a core (C2) comprising Cu, and Sn or a solder containing Sn that covers the core (C2).

Description

JOINTING MATERIAL COMPOSITION, BONDING MATERIAL COMPOSITION MANUFACTURING METHOD, BONDING FILM, JOINTED PRODUCT MANUFACTURING METHOD, AND JOINTED BODY

TECHNICAL FIELD The present invention relates to a bonding material composition, a method for manufacturing a bonding material composition, a bonding film, a method for manufacturing a bonded body, and a bonded body, and particularly to a bonding material for connecting a semiconductor element and a substrate such as a circuit board or a ceramic substrate. The present invention relates to a bonding material composition, a bonding film, a method for manufacturing a bonded body using the bonding material composition and the bonding film, and a bonded body.

A semiconductor device generally comprises a step of forming a die mount material for bonding a semiconductor element on an element carrying portion of a lead frame or a circuit electrode portion of an insulating substrate, and a die mount material on the lead frame or on the circuit electrode. A step of mounting a semiconductor element on the surface and joining the element holding portion of the lead frame or the circuit electrode portion of the insulating substrate to the semiconductor element; It is manufactured through a wire bonding process for electrical bonding and a molding process for resin-coating the thus assembled semiconductor device.

Here, a bonding material is used when bonding the element carrying portion of the lead frame or the circuit electrode portion of the insulating substrate and the semiconductor element. For example, lead solder containing 85% by mass or more of lead, which has a high melting point and heat resistance, has been widely used as a bonding material for power semiconductors such as IGBTs and MOS-FETs. However, in recent years, the harmfulness of lead has been viewed as a problem, and there is an increasing demand for lead-free joining materials.

In addition, compared to Si power semiconductors, SiC power semiconductors are characterized by low loss and the ability to operate at high speeds and high temperatures, and are expected to be next-generation power semiconductors. Such SiC power semiconductors are theoretically capable of operating at temperatures above 200°C. Improvement is desired.

Against this background, in recent years, various lead-free, high-melting-point joining materials have been evaluated. Au-based alloys such as Au--Sn-based alloys and Au--Ge-based alloys have been disclosed as such high-melting-point lead-free type bonding materials (for example, Patent Document 1). It is attracting attention for its good thermal conductivity and chemical stability. However, since such Au-based alloy materials contain precious metals, the material costs are high, and in order to obtain better mounting reliability, an expensive high-temperature vacuum reflow apparatus is required. Not yet.

Therefore, as a method for bonding semiconductor elements that operate at high temperatures, a bonding material containing Cu and Sn is interposed between the semiconductor element and the substrate, and heated at a temperature higher than the melting point of Sn to convert the bonding material into Cu ₆ Sn ₅ . A bonding method called Transient Liquid Phase Sintering (TLP method) that uses an intermetallic compound (IMC) composed of Cu and Cu _Sn is attracting attention, and this bonding method A joining method and a joining film using are disclosed (see, for example, Patent Documents 2 and 3).

In Patent Document 2, a paste-like bonding agent containing Cu particles and Sn particles is interposed between the bonding surface of a semiconductor chip and the bonding surface of a substrate, and heated at a temperature higher than the melting point of Sn to bond Cu and Sn together. is transitionally liquid-phase sintered to make the bonding agent a composition containing Cu ₆ Sn ₅ and Cu ₃ Sn, and further heated in the temperature range of 232° C. to 415° C. to convert the Cu ₆ Sn ₅ of the bonding agent into Cu ₃ Sn. A bonding method is disclosed in which the ratio of Cu ₃ Sn in the bonding agent is changed to increase the ratio of Cu ₃ Sn to obtain a single phase of Cu 3 Sn or an equilibrium structure of Cu ₃ Sn phase and Cu particles.

Patent Document 3 discloses a bonding film containing first metal particles and second metal particles capable of forming an intermetallic compound such as a Cu—Sn-based compound, a resin, and at least one of phosphines and sulfides. It is

In addition, as a bonding paste that does not use the transitional liquid phase sintering method, the average particle size composed of a central core made of Cu and a coating layer made of Cu ₆ Sn ₅ covering the central core is 0.05 to 0.05. A bonding paste obtained by mixing a fine powder of 1 μm and an organic solvent is disclosed (see, for example, Patent Document 4). After interposing this bonding paste between the first and second members to be joined, a pressure of at least 0.1 MPa is applied under a nitrogen gas atmosphere or a formic acid gas atmosphere so that the first and second members to be joined are in close contact with each other. was added and heated at a temperature of 250 to 400°C for 5 to 120 minutes, the Cu particles diffused substantially uniformly inside the intermetallic compound of Cu ₆ Sn ₅ , and Cu ₃ Sn It is said that it is possible to achieve bonding with high initial bonding strength and high bonding strength during thermal cycles.

Japanese Patent Application Laid-Open No. 2006-032888 Japanese Patent No. 6061248 WO2017/138255 Japanese Patent No. 6753349

However, in the bonding method described in Patent Document 2, since it is difficult to remove oxides formed on the surfaces of the Cu particles, when the bonding agent is heated, Sn in the molten liquid phase is less likely to wet the surfaces of the Cu particles. Since unreacted Cu particles remain in the bonding layer, there is a problem that shear strength and heat dissipation are low. In addition, when melted Sn solidifies, it becomes bulk, so that the elongation of the bonding layer is small, so that the high operating temperature of the power semiconductor lowers the shear strength, resulting in low heat resistance. Furthermore, in order to change Cu ₆ Sn ₅ to Cu ₃ Sn and increase the ratio of Cu ₃ Sn, heating must be performed in two stages, which is a problem in that it takes time and effort.

In the bonding method described in Patent Document 3, since at least one of phosphines and sulfides is included, the oxide formed on the Cu particle surface is removed, but the Sn liquid phase has fluidity, so the Sn liquid phase was locally biased, unreacted Cu particles still remained in the bonding layer, and the shear strength and heat dissipation were insufficient.

In the bonding film described in Patent Document 4, since the melting point of Cu ₆ Sn ₅ that coats the central core made of Cu is high, the bonding layer is formed by sintering by using fine particles and applying pressure. to form Since the bonding layer is a sintered body, there are many voids. For this reason, there are problems of low conductivity and heat dissipation, and low elongation and low heat resistance. In addition, since it uses finer particles, it can be applied to thin films, but it is expected that formation of thick films will be difficult.

Accordingly, the present invention provides a bonding material composition capable of improving the shear strength, heat resistance, electrical conductivity and heat dissipation of a bonding layer, a method for manufacturing the bonding material composition, a bonding film, a method for manufacturing a bonded body, and bonding. The purpose is to provide the body.

In order to solve the above problems, the bonding material composition according to the present invention includes metal particles (P) including first metal particles (P1) and second metal particles (P2), and flux, The first metal particles (P1) are composed of a core (C1) made of Cu and a Cu ₂ O layer covering the core (C1), and the second metal particles (P2) are composed of a core (C1) made of Cu. C2) and Sn covering the core (C2) or solder containing Sn.

In the bonding material composition, the first metal particles (P1) preferably have an average particle size of 1 to 20 μm, and the second metal particles (P2) preferably have an average particle size of 1 to 10 μm.

In the bonding material composition, Sn covering the core (C2) or Sn in a solder containing Sn is preferably 55 to 65% by mass.

In the bonding material composition, the diffraction intensity of the Cu (111) plane measured by X-ray diffraction of the first metal particles (P1) is H1, and the diffraction intensity of the Cu ₂ O (111) plane is is H2, the oxidation degree H of the first metal particles (P1) represented by the following formula 1 is preferably 0.05 to 0.3.
H=H2/(H1+H2) [Formula 1]

In the bonding material composition, the metal particles (P) further include third metal particles (P3), and the third metal particles (P3) are Sn particles or Sn-containing solder particles. is preferred.

Further, the bonding material composition covers the core (C2) with respect to the total amount of 100% by mass of the Cu of the core (C1) and the Cu of the core (C2), or Sn or a solder containing Sn and the ratio of Sn in the Sn particles or Sn-containing solder particles is preferably 55 to 65% by mass.

In addition, in the bonding material composition, it is preferable that the flux has reducing properties and that the reaction product does not contain water.

In addition, in the bonding material composition, the flux preferably contains at least one of phosphines represented by the following general formula (1) and sulfides represented by the following general formula (2). However, in the following general formulas (1) and (2), each R independently represents an organic group, and each R may be the same or different.

Further, in the bonding material composition, it is preferable that the content of the flux is 0.05 to 0.5% by mass with respect to the metal particles (P).

In addition, it is preferable that the content of the metal particles (P) in the bonding material composition is 80 to 95% by mass with respect to the total amount of the bonding material composition.

Further, the bonding material composition is heated at 240° C. or higher to form a bonding layer that bonds the first member and the second member, and the bonding layer includes Cu particles of Cu and Sn. It is preferable to have a network structure joined by a compound of

Also, the bonding material composition preferably contains a thermosetting resin.

In order to solve the above problems, the method for producing a bonding material composition according to the present invention includes a step of mixing and stirring the first metal particles (P1) and the second metal particles (P2). It is characterized by

Further, in order to solve the above problems, a bonded film according to the present invention is a bonded film having a bonding material layer, wherein the bonding material layer is formed using the bonding material composition according to any one of the above. It is characterized by being

Further, in the bonding film, it is preferable that the bonding material layer has a thickness of 10 to 100 μm.

Further, in order to solve the above problems, a method for manufacturing a joined body according to the present invention provides a joining method for joining a first member and a second member with a joining layer using any of the joining material compositions described above. In the method for manufacturing a body, the bonding material composition is interposed between the first member and the second member and heated at 240° C. or higher to convert the flux into the first metal particles. The Cu ₂ O layer of (P1) is removed, the Sn of the second metal particles (P2) or the Sn-containing solder melts, and the Cu of the core (C1) and the core (C2 ) reacts with the Cu to form the bonding layer having a network structure in which Cu particles are bonded by a compound of Cu and Sn.

Further, in order to solve the above problems, a method for manufacturing a bonded body according to the present invention provides a bonded body in which a first member and a second member are bonded by a bonding layer using any one of the bonding films described above. In the manufacturing method, the bonding material layer is interposed between the first member and the second member, and heated at 240° C. or higher to convert the flux into the first metal particles (P1). The Cu ₂ O layer of the second metal particles (P2) is removed, the Sn of the second metal particles (P2) or the Sn-containing solder melts, and the Cu of the core (C1) and the Cu of the core (C2) The bonding layer is characterized in that it reacts with Cu to form the bonding layer having a network structure in which Cu particles are bonded by a compound of Cu and Sn.

Further, in order to solve the above problems, a joined body according to the present invention is a joined body in which a first member and a second member are joined by a joining layer using any of the joining material compositions described above. The bonding layer is formed by heating the bonding material composition at 240° C. or higher.

Further, in order to solve the above problems, a joined body according to the present invention is a joined body in which a first member and a second member are joined by a joining layer using any one of the joining films described above. and the bonding layer is formed by heating the bonding material layer at 240° C. or higher.

In the above bonded body, the bonding layer preferably has a network structure in which Cu particles are bonded with a compound of Cu and Sn.

In the bonded body described above, the bonding layer preferably has a thickness of 10 to 300 μm.

INDUSTRIAL APPLICABILITY According to the present invention, there is provided a bonding material composition capable of improving the shear strength, heat resistance, conductivity and heat dissipation of a bonding layer, a method for manufacturing the bonding material composition, a bonding film, a method for manufacturing a bonded body, and bonding. body can be provided.

A bonding material composition according to an embodiment of the present invention will be described below.

A bonding material composition according to one embodiment of the present invention includes metal particles (P) including first metal particles (P1) and second metal particles (P2), and flux. The particles (P1) are composed of a core (C1) made of Cu and a Cu ₂ O layer covering the core (C1), and the second metal particles (P2) are composed of a core (C2) made of Cu and the core (C2). C2) is coated with Sn or a solder containing Sn.

The bonding material composition of the present invention can be used as a bonding paste for bonding a semiconductor element and a substrate. Further, the bonding material composition of the present invention can also be used as a bonding material layer of a bonding film having a bonding material layer by being formed into a film.

Each component of the bonding material composition of the present embodiment will be described in detail below.

(First metal particles (P1))
The first metal particles (P1) are composed of a core (C1) made of Cu and a Cu ₂ O layer covering the core (C1). The Cu ₂ O layer can be formed by heating Cu particles in an oven or the like at 170 to 300° C. for 30 minutes to 50 hours. Note that the heating temperature and the heating time can be appropriately adjusted as long as the Cu ₂ O layer is formed.

The degree of oxidation H of the first metal particles (P1) is preferably 0.05 to 0.3, more preferably 0.05 to 0.2. The degree of oxidation H is obtained when the diffraction intensity of the Cu (111) plane of the first metal particles (P1) measured by X-ray diffraction is H1, and the diffraction intensity of the Cu ₂ O (111) plane is H2. , can be obtained by the following formula 1.
H=H2/(H1+H2) [Formula 1]

According to X-ray diffraction using CuKα as an X-ray source, the (111) plane of copper (I) oxide (Cu ₂ O) has a peak near 2θ = 36°, while the (111) plane of copper (Cu) The plane has a peak near 2θ=43°. Note that only copper (I) oxide (Cu ₂ O) exists as copper oxide, and copper (II) oxide (CuO) does not exist under these conditions. Thus, in X-ray diffraction measurement, the peak height of the Cu (111) plane present near 2θ=43° is H1, and the peak height of the Cu ₂ O (111) plane present near 2θ=36° is H2. Then, the degree of oxidation H can be obtained from the X-ray diffraction peak intensity ratio (H2/[H1+H2]).

When the degree of oxidation H is less than 0.05, the reaction between the Cu in the core (C1) of the first metal particles (P1) and the Sn or Sn-containing solder in the second metal particles (P2) is partially As a result, it becomes difficult to obtain a uniform structure throughout the bonding layer. When the degree of oxidation H exceeds 0.3, the oxide film is too thick and the oxide film is not sufficiently removed by the flux. The reaction of the Sn particles (P2) or the solder containing Sn may also be insufficient, and as a result, the shear strength, heat resistance, and heat dissipation properties of the bonding layer may decrease. Furthermore, if the oxidation degree H exceeds 0.5, the removal of the oxide film by the flux may not be done in time, and the electrical conductivity of the bonding layer may be lowered.

The degree of oxidation H can be adjusted by adjusting the heating temperature and heating time of the core (C1).

The average particle size of the first metal particles (P1) is preferably 1-20 μm, more preferably 5-8 μm. If the average particle size of the first metal particles (P1) is less than 1 μm, they tend to aggregate, the catalytic effect becomes too strong, and the dispersibility with the thermosetting resin may be reduced. There is a risk that the shear strength, heat resistance, electrical conductivity, and heat dissipation of the bonding layer may be reduced. When the average particle size of the first metal particles (P1) is more than 20 μm, it becomes difficult to uniformly react with Sn of the second metal particles (P2) when the bonding material composition is heated at 240° C. or higher. In this case, a joining layer having a uniform structure cannot be obtained, and the shear strength and heat dissipation of the joining layer may be lowered. In addition, the bonding layer becomes too thick, which may reduce the reliability. Furthermore, if the average particle size of the first metal particles (P1) exceeds 25 μm, the wettability of the solder may deteriorate and the electrical conductivity may decrease.

Further, when the bonding material composition is formed into a film to form the bonding material layer of the bonding film, the average particle diameter of the first metal particles (P1) is preferably 1 to 10 μm. If the average particle diameter of the first metal particles (P1) exceeds 10 μm, the thickness of the bonding material layer becomes too large, making it difficult to handle as a film and impairing mass productivity.

The average particle diameter of each particle in the present invention is determined by the median diameter (the particle diameter at which the cumulative frequency reaches 50%: D50). Specifically, a particle group extracted and separated from raw material powder or paste is determined by measurement using a laser diffraction scattering type particle size distribution analyzer.

(Second metal particles (P2))
The second metal particles (P2) are composed of a core (C2) made of Cu and Sn or a solder containing Sn covering the core (C2). The term “coating” as used herein means that half or more of the surface area of the core (C2) is covered. The second metal particles (P2) can be obtained by coating the core (C2) with Sn or solder containing Sn by electroless plating. Solders containing Sn are lead-free solders, tin (Sn)-nickel (Ni)-copper (Cu) system, tin (Sn)-silver (Ag)-copper (Cu) system, tin (Sn)- Zinc (Zn) - Bismuth (Bi) system, Tin (Sn) - Copper (Cu) system, Tin (Sn) - Silver (Ag) - Indium (In) - Bismuth (Bi) system, Tin (Sn) - Zinc ( Zn)-aluminum (Al) system or the like can be used.

The average particle diameter of the second metal particles (P2) is preferably 1-10 μm, more preferably 1-5 μm, and even more preferably 1.5-3 μm. In order to avoid residual Sn with low heat resistance and densely fill the second metal particles (P2), the average particle size of the second metal particles (P2) should be less than that of the first metal particles (P1). is also preferably smaller than the average particle size of

By setting the average particle diameter of the second metal particles (P2) to 1 μm or more, the Cu particles of the first metal particles (P1) are formed inside the bonding layer formed by heating the bonding material composition at 240° C. or more. Between the Cu ₃ Sn formed by the reaction of Sn wetting and spreading on the surface of the second metal particle (P2) and the Cu ₃ Sn particles formed by the reaction of Sn with the Cu particles of the core (C2) of the second metal particles (P2) Since voids are easily formed, the elongation of the bonding layer is increased, and the heat resistance is improved without lowering the shear strength even under the high operating temperature of the power semiconductor.

By setting the average particle diameter of the second metal particles (P2) to 10 μm or less, when the bonding material composition is heated at 240° C. or higher, the second metal particles ( P2) enters, the reaction progresses uniformly, and a bonding layer with a uniform structure is obtained, so that the shear strength and heat dissipation of the bonding layer are improved.

When the average particle diameter of the second metal particles (P2) is less than 1 μm, the melting rate of Sn or Sn-containing solder covering the core (C2) is lower than that of Cu ₂ O of the first metal particles (P1). In addition, the surface of Sn or Sn-containing solder covering the core (C2) is likely to be oxidized, resulting in poor wettability of the solder. As a result, the shear strength, heat resistance, electrical conductivity, and heat dissipation of the bonding layer may all deteriorate. When the second metal particles (P2) have an average particle size of more than 10 μm, when the bonding material composition is heated at 240° C. or higher, it becomes difficult to uniformly react with Cu of the first metal particles (P1). In this case, a joining layer having a uniform structure cannot be obtained, and the shear strength and heat dissipation of the joining layer may be lowered. Furthermore, if the average particle size of the second metal particles (P2) exceeds 12 μm, the wettability of the solder may deteriorate and the conductivity of the bonding layer may decrease.

The bonding material composition has a Sn ratio of 55 to 65 in Sn or Sn-containing solder covering the core (C2) with respect to the total amount of 100% by mass of Cu in the core (C1) and Cu in the core (C2). % by mass is preferred. When the proportion of Sn is less than 55% by mass, when the bonding material composition is heated at 240° C. or higher, Sn is used in the reaction of the core (C2) with Cu, and the first metal particles (P1) are formed. Since it becomes difficult to react with Cu of the core (C1), a bonding layer having a uniform structure cannot be obtained, and the shear strength and heat dissipation of the bonding layer may be lowered. In addition, the compound of Cu and Sn cannot be sufficiently formed, and the heat resistance and electrical conductivity of the bonding layer may deteriorate. When the proportion of Sn exceeds 65% by mass, most of the Cu in the core (C1) of the first metal particles (P1) becomes Cu ₃ Sn, and the amount of Cu decreases, resulting in low heat dissipation. Further, when the proportion of Sn is more than 65% by mass, the molten Sn solidifies into bulk without reacting with Cu, and the gap between the first metal particles (P1) and the second metal particles (P2) , the elongation of the bonding layer is reduced and the heat resistance may be lowered.

(Third metal particles (P3))
In the bonding material composition, the ratio of Sn in the Sn or Sn-containing solder covering the core (C2) is 55% by mass with respect to the total amount of 100% by mass of Cu in the core (C1) and Cu in the core (C2) %, the metal particles (P) contain Sn particles or Sn-containing solder particles as the third metal particles (P3), so long as the proportion of the total Sn does not exceed 65% by mass. good too. That is, the bonding material composition is based on the total amount of 100% by mass of Cu of the core (C1) and Cu of the core (C2), Sn or Sn in the solder containing Sn covering the core (C2), and Sn particles Alternatively, the ratio of Sn in the solder particles containing Sn is preferably 55 to 65% by mass. Solder particles containing Sn are lead-free solders, tin (Sn)-nickel (Ni)-copper (Cu) system, tin (Sn)-silver (Ag)-copper (Cu) system, tin (Sn) - zinc (Zn) - bismuth (Bi) system, tin (Sn) - copper (Cu) system, tin (Sn) - silver (Ag) - indium (In) - bismuth (Bi) system, tin (Sn) - zinc A (Zn)-aluminum (Al) system or the like can be used.

(flux)
The bonding material composition contains flux. Flux is not particularly limited, and flux generally used for soldering or the like can be used.

Examples of the flux include zinc chloride, mixtures of zinc chloride and inorganic halides, mixtures of zinc chloride and inorganic acids, molten salts, phosphoric acid, phosphoric acid derivatives, organic halides, hydrazine, amine compounds, organic acids and pine resin and the like. Only one kind of the above flux may be used, or two or more kinds thereof may be used in combination.

Examples of the molten salt include ammonium chloride. Examples of the organic acid include lactic acid, citric acid, stearic acid, glutamic acid and glutaric acid. Examples of the pine resin include activated pine resin and non-activated pine resin. The flux may be an organic acid having a carboxyl group, or may be rosin.

Examples of the organic acid having a carboxyl group include glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, octadecanedioic acid, nonadecanedioic acid, eicosanedioic acid, and the like. Among them, adipic acid, suberic acid, sebacic acid and dodencanedioic acid are preferred, and examples thereof include sebacic acid.

The above pine resin is a rosin whose main component is abietic acid. Examples of the rosins include abietic acid and acryl-modified rosins.

Examples of the above amine compounds include cyclohexylamine, dicyclohexylamine, benzylamine, benzhydrylamine, imidazole, benzimidazole, phenylimidazole, carboxybenzimidazole, benzotriazole, and carboxybenzotriazole.

In the present invention, flux also includes a compound that functions as a flux to remove an oxide film on a metal surface, that is, has a reducing property. Such compounds include compounds containing one or more phosphorus or sulfur in their molecular structures. Compounds containing one or more phosphorus or sulfur in the molecular structure include organic phosphorus compounds, organic sulfur compounds, and the like.

Compounds containing one or more phosphorus or sulfur in their molecular structure do not contain water in the reaction product, i.e., combine with oxygen atoms without the formation of water, and remove oxygen atoms from metal oxides. can be done. In general, a product with a large latent heat of vaporization, such as water, causes violent bumping by heating and induces void formation in the structure. Therefore, formation of voids can be prevented by using a flux containing no water as a reaction product.

In addition, compounds that contain one or more phosphorus or sulfur in their molecular structure are less likely to absorb moisture and bleed out, so there is no need to wash the flux after reflow, unlike general fluxes such as carboxylic acids.

The organic phosphorus compound is preferably at least one selected from phosphines and phosphites. Phosphines include, for example, triphenylphosphine, tris(4-methylphenyl)phosphine, methyldiphenylphosphine, diethylphenylphosphine, cyclohexyldiphenylphosphine, 4-(diphenylphosphino)styrene, methylenebis(diphenylphosphine), ethylenebis(diphenyl phosphine), trimethylenebis(diphenylphosphine), tetramethylenebis(diphenylphosphine) can be used. Further, as phosphites, for example, trimethyl phosphite, triethyl phosphite, triisopropyl phosphite, tributyl phosphite, trioctyl phosphite, tris(2-ethylhexyl) phosphite, triisodecyl phosphite, trioleyl phosphite, triphenyl phosphite, tri-p-tolyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tristearyl phosphite, tris(nonyl phosphite) phenyl), trilauryl trithiophosphite can be used.

The organic sulfur compound is preferably at least one selected from sulfides, disulfides, trisulfides and sulfoxides. Examples of sulfides include bis(4-methacryloylthiophenyl) sulfide, bis(4-hydroxyphenyl) sulfide, bis(4-aminophenyl) sulfide, 2-methylthiophenothiazine, diallyl sulfide, ethyl 2-hydroxyethyl sulfide, dia Mylsulfide, hexylsulfide, dihexylsulfide, n-octylsulfide, phenylsulfide, 4-(phenylthio)toluene, phenyl p-tolylsulfide, 4-tert-butyldiphenylsulfide, di-tert-butylsulfide, diphenylenesulfide, fur Furyl sulfide, bis(2-mercaptoethyl) sulfide can be used. Examples of disulfides include diethyl disulfide, dipropyl disulfide, dibutyl disulfide, amyl disulfide, heptyl disulfide, cyclohexyl disulfide, bis(4-hydroxyphenyl) disulfide, bis(3-hydroxyphenyl) disulfide, diphenyl disulfide, and benzyl disulfide. can be used. Examples of trisulfides that can be used include dimethyltrisulfide and diisopropyltrisulfide. As sulfoxides, dimethylsulfoxide, dibutylsulfoxide, di-n-octylsulfoxide, methylphenylsulfoxide, diphenylsulfoxide, dibenzylsulfoxide and p-tolylsulfoxide can be used.

In particular, the flux preferably contains at least one of phosphines represented by the following general formula (1) and sulfides represented by the following general formula (2). However, in the following general formulas (1) and (2), each R independently represents an organic group, and each R may be the same or different.

In the above general formulas (1) and (2), each R is independently selected from an alkyl group, an aryl group, an organic group having a functional group, an organic group having a heteroatom, and an organic group having an unsaturated bond. and at least one of R is preferably an aryl group.

The above alkyl group may be linear, branched or cyclic, and may have a substituent. Alkyl groups are preferably linear or branched. The alkyl group preferably has 3 or more carbon atoms, more preferably 4 to 18 carbon atoms, and even more preferably 6 to 15 carbon atoms. Specific examples of such alkyl groups include propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, stearyl and isostearyl groups.

The aryl group may have a substituent and preferably has 6 to 10 carbon atoms. Examples of such aryl groups include phenyl, tolyl, xylyl, cumenyl and 1-naphthyl groups.

The organic group having the functional group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 3 carbon atoms. Moreover, the functional group of the organic group includes a chloro group, a bromo group, a fluoro group, and the like. Further, specific examples of organic groups having such functional groups include chloroethyl, fluoroethyl, chloropropyl, dichloropropyl, fluoropropyl, difluoropropyl, chlorophenyl and fluorophenyl groups. mentioned.

The organic group having a heteroatom preferably has 3 or more carbon atoms, more preferably 4 to 18 carbon atoms, and even more preferably 6 to 15 carbon atoms. Moreover, a nitrogen atom, an oxygen atom, a sulfur atom, etc. are mentioned as a heteroatom which the said organic group has. Examples of such heteroatom-containing organic groups include dimethylamino, diethylamino, diphenylamino, methylsulfoxide, ethylsulfoxide and phenylsulfoxide groups.

The organic group having an unsaturated bond preferably has 3 or more carbon atoms, more preferably 4 to 18 carbon atoms, and even more preferably 6 to 15 carbon atoms. Specific examples of organic groups having such unsaturated bonds include propenyl, propynyl, butenyl, butynyl, oleyl, phenyl, vinylphenyl and alkylphenyl groups. Among them, it is more preferable to have a vinylphenyl group.

Further, in the above general formulas (1) and (2), each R is independently a vinyl group, an acrylic group, a methacrylic group, a maleic acid ester group, a maleic acid amide group, a maleic acid imide group, It preferably has at least one selected from primary amino groups, secondary amino groups, thiol groups, hydrosilyl groups, hydroboron groups, phenolic hydroxyl groups and epoxy groups. Among them, it is more preferable to have a vinyl group, an acrylic group, a methacrylic group, or a secondary amino group. Specifically, the phosphines preferably include p-styryldiphenylphosphine. Such a compound is preferable in that it has a highly reactive vinyl group and thus exhibits low bleed-out.

Sulfides include at least one of bis(hydroxyphenyl)sulfide, bis(acryloylthiophenyl)sulfide, 2-methylthiophenothiazine, bis(2-methacryloylthioethyl)sulfide and bis(methacryloylthiophenyl)sulfide. is preferred, and at least one of bis(acryloylthiophenyl)sulfide and bis(methacryloylthiophenyl)sulfide is more preferred. These compounds are preferable in that they have a highly reactive phenolic hydroxyl group, acrylic group, and methacrylic group, so that bleeding out is low. Among them, compounds having an acrylic group or a methacrylic group are most preferable.

In addition, phosphines and sulfides can be used alone, or both can be used in combination.

In addition, such phosphines and sulfides can form a copolymer with a maleimide resin when the thermosetting resin described later contains a maleimide resin, and thus also act as a thermosetting resin component. In addition, phosphines and sulfides are less likely to absorb moisture, have a sufficiently large molecular weight, and are polymerizable, and therefore can effectively prevent bleeding out when used as a flux component. Therefore, by using such phosphines and sulfides instead of alcohols and carboxylic acids that easily absorb moisture, the risk of bleeding out can be reduced without flux cleaning, and sufficient reliability can be achieved, especially after moisture absorption. can guarantee reflow resistance.

The bonding material composition preferably has a flux content of 0.05 to 0.5% by mass with respect to the metal particles (P). If the flux content is less than 0.05% by mass, the Cu ₂ O layer of the first metal particles (P1) cannot be sufficiently removed, and the wettability of Sn and the relationship between Sn and the first metal particles (P1) The reactivity of Cu in the core (C1) of is lowered. On the other hand, if the flux content is more than 0.5% by mass, the flux remains and inhibits the reaction between Sn and Cu in the core (C1) of the first metal particle (P1), resulting in heat resistance and heat dissipation. , would be expected to result in lower conductivity. Depending on the type of flux, the residual flux may absorb moisture or bleed out, which may adversely affect the device, or promote the diffusion reaction between Cu and Sn more than necessary to grow diffusion voids. There is a risk that the strength and elongation of the bonding material will be reduced, resulting in lower reliability.

In order to make the flux content ratio 0.05 to 0.5% by mass with respect to the metal particles (P), the surface of the first metal particles (P1) is modified with flux, or the bonding material composition is A small amount of flux may be added.

In order to modify the surface of the first metal particles (P1) with a flux, the first metal particles (P1) are immersed in a flux solution, and the flux is applied to the first metal particles (P1) using an ultrasonic device. coordinated to the surface. When such a method is used, there is no need to add an excessive amount of flux compared to adding flux to the bonding material composition, and inhibition of reactions due to residual flux and effects on devices due to flux components can be minimized. , an improvement in reliability can be expected.

The flux content when modifying the surface of the first metal particles (P1) with flux can be adjusted by the output of the ultrasonic device and the stirring time. Further, the flux content in the case where the surface of the first metal particles (P1) is modified with flux can be specified using FT-IR (Fourier transform infrared spectroscopy) measurement.

(Thermosetting resin)
The bonding material composition contains a thermosetting resin when formed into a film and used as a bonding material layer of a bonding film, but preferably does not contain a thermosetting resin when used as a bonding paste. By including a thermosetting resin in the bonding material composition, when the bonding material composition is formed into a film and used as a bonding material layer of a bonding film, film formability and handleability are improved. Also, the adhesiveness to semiconductor elements, lead frames, etc. is improved at the time of bonding. Furthermore, the bonding layer formed by heating the bonding material composition plays a role in relieving stress generated between the semiconductor element and the lead frame or the like due to thermal cycles. For this reason, when the viscosity of the flux is low, it is particularly preferable to include a thermosetting resin.

The thermosetting resin is, in particular, a maleic acid imide resin containing a maleic acid imide compound containing two or more units of imide groups in one molecule, from the viewpoint of heat resistance and film-forming properties when metal particles (P) are mixed. (hereinafter sometimes referred to as "maleimide resin") or an epoxy resin having a molecular skeleton derived from a glycidyl ether of an aliphatic diol, and more preferably a maleic acid imide resin. In particular, since a thermosetting resin containing any of the resins described above has excellent stress relaxation properties, the heat resistance of the bonding layer formed by heating the bonding material composition is improved.

The maleic acid imide resin can be obtained, for example, by condensing maleic acid or its anhydride with a diamine or polyamine. In addition, the maleic acid imide resin preferably contains a skeleton derived from an aliphatic amine having 10 or more carbon atoms from the viewpoint of stress relaxation, and in particular, has 30 or more carbon atoms and is represented by the following structural formula (3). Those having a skeleton such as Moreover, the maleic acid imide compound preferably has a number average molecular weight of 3,000 or more.

The maleic acid imide resin contains a skeleton derived from an acid component other than maleic acid, such as benzenetetracarboxylic acid or its anhydride, hydroxyphthalic acid bisether or its anhydride. etc., can be adjusted. Phenol novolac resins, radical generators, and the like are preferable as curing agents for maleic acid imide resins.

As such a maleic acid imide resin, for example, bismaleimide resins represented by the following structural formulas (4) to (6) are preferably used.

However, in the above formula (5), n is an integer of 1-10. Further, in the above formulas (4) to (6), the “X” portion is the skeleton of “C ₃₆ H ₇₂ ” represented by the following structural formula (7). In addition, in the following formula (7), "*" means a binding site with N.

Examples of epoxy resins having molecular skeletons derived from glycidyl ethers of aliphatic diols include ethylene glycol-modified epoxy resins, propylene glycol-modified epoxy resins, butanediol-modified epoxy resins, and the like. These epoxy resins are preferred from the viewpoint of flexibility. In addition, from the viewpoint of achieving both adhesive strength and flexibility, it is preferable to use such an epoxy resin by mixing it with a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, or a phenoxy resin, which is an epoxy resin with a large molecular weight. preferable.

In addition, acid anhydrides, phenol novolac resins, amines, imidazole compounds, dicyandiamide, and the like can be selected as curing agents for epoxy resins as described above. Among them, phenol novolak resins and imidazole compounds are preferred.

The thermosetting resin preferably further contains a phenol novolac resin. For example, by using a combination of the maleic acid imide resin or epoxy resin and the phenol novolac resin, the phenol novolak resin acts as a curing agent, further improving the adhesiveness of the thermosetting resin.

The content of the thermosetting resin in the bonding material composition according to the present embodiment is preferably 4-30% by mass, more preferably 6-20% by mass. By setting the content of the thermosetting resin to 4% by mass or more, the adhesiveness to semiconductor elements, lead frames, etc. is improved at the time of bonding. In addition, the bonding layer formed by heating the bonding material composition is excellent in relieving stress generated between the semiconductor element and the lead frame or the like due to thermal cycles. If the content of the thermosetting resin is more than 30% by mass, the heat dissipation may deteriorate.

When forming the bonding material layer of the bonding film with the bonding material composition, the content of the thermosetting resin in the bonding material composition is 6 to 9 from the viewpoint of the balance between the film formability and handleability and heat dissipation. % by mass is preferred.

The thermosetting resin may consist of only one type of resin, or may be a mixture of two or more types of resin. Moreover, you may further contain resin other than the above as needed.

The content of metal particles (P) in the bonding material composition is preferably 80 to 95% by mass with respect to the total amount of the bonding material composition. If the content of the metal particles (P) is less than 80% by mass, the release is lowered. When the content of the metal particles (P) is more than 95% by mass, the contents of the flux and the thermosetting resin are reduced, so the wettability of Sn and the relationship between Cu and Sn in the first metal particles (P1) Reactivity, adhesion to semiconductor elements, lead frames, etc. during bonding, and stress relaxation after bonding are reduced.

In addition to the above components, the bonding material composition according to the present embodiment may contain various additives within the scope of the present invention. Examples of such additives include dispersants, radical polymerization initiators, leveling agents, plasticizers, and the like, which can be appropriately selected as necessary.

Next, a method for manufacturing the bonding material composition will be described. The method for producing the bonding material composition is not particularly limited. It can be obtained by mixing the components constituting the bonding material composition described above, and then subjecting the composition to stirring, dispersion, or the like. The surface of the first metal particles (P1) is preferably modified in advance with the flux by the method described above. Devices for mixing, stirring, dispersing, etc. of these are not particularly limited, and include a three-roll mill, a planetary mixer, a planetary mixer, a rotation-revolution type stirring device, a milling machine, a twin-screw kneader, A thin layer shear disperser or the like can be used.

Next, the bonding film according to the present invention will be explained. The bonding film has at least a bonding material layer for bonding a semiconductor element and a lead frame or the like, and this bonding material layer is formed using the bonding material composition described above. From the viewpoint of improving the film formability, the bonding material composition may further contain a solvent.

As a method of forming the bonding material layer, first, the bonding material composition is formed into a film. The method for forming the bonding material composition into a film is not particularly limited, and conventional methods can be used, such as inkjet printing, screen printing, jet printing, dispenser, jet dispenser, comma coater, slit coater, A die coater, gravure coater, slit coat, letterpress printing, intaglio printing, gravure printing, stencil printing, bar coater, applicator, spray coater, electrodeposition coating, and the like can be used.

The bonding material layer is obtained by drying the solvent of the bonding material composition formed into a film. As a drying method, drying by standing at room temperature, drying by heating, or drying under reduced pressure can be used. Hot plate, hot air dryer, hot air heating furnace, nitrogen dryer, infrared dryer, infrared heating furnace, far infrared heating furnace, microwave heating device, laser heating device, electromagnetic heating device for heat drying or vacuum drying , a heater heating device, a steam heating furnace, a hot plate press device, or the like can be used. The drying temperature and time are preferably adjusted according to the type and amount of the dispersion medium used. For example, drying is preferably performed at 50 to 180° C. for 1 to 120 minutes.

The bonding material layer may be peeled off after forming the bonding material layer in the form of a film on the molding substrate. The molding substrate is not particularly limited, but for example, polyethylene terephthalate, polytetrafluoroethylene, polyimide, PEEK, aluminum, glass, alumina, silicon nitride, and stainless steel can be used. Also, a heat-resistant substrate or cloth coated or impregnated with the above material may be used as the molding substrate.

The bonding film may have a release film bonded to the surface of the bonding material layer to protect the surface of the bonding material layer until the bonding material layer is used.

The bonding material layer preferably has a thickness of 10 to 100 μm.

Next, a method for using the bonding material composition and the bonding material layer described above, that is, a method for manufacturing a bonded body will be described.

Bonded bodies include semiconductor devices and electronic components. Specific examples of semiconductor devices include diodes, rectifiers, thyristors, MOS (Metal Oxide Semiconductor) gate drivers, power switches, power MOSFETs (Metal Oxide Semiconductor Field-Effect Transistors), and IGBTs (Insulated Gate Bipolar Transistors). istor), Schottky diode, Examples include power modules, transmitters, amplifiers, LED modules, etc., which include fast recovery diodes and the like.

First, the bonding material composition or bonding material layer described above is interposed between the first member and the second member. That is, by bringing a portion of the first member to be bonded to the second member and a portion of the second member to be bonded to the first member into contact, the first member and the second member are bonded by the bonding material. They are laminated through a composition or a bonding material layer. Here, the first member is not particularly limited, but may be a lead frame, a pre-wired tape carrier, a rigid wiring board, a flexible wiring board, a pre-wired glass substrate, a pre-wired silicon wafer, or a wafer level CSP. (Wafer Level Chip Size Package). The second member is not particularly limited, and includes active elements such as transistors, diodes, light emitting diodes and thyristors; passive elements such as capacitors, resistors, resistor arrays, coils and switches; The bonding material composition according to is suitably used for semiconductor devices that operate at high temperatures, particularly power semiconductors.

Next, the bonding material composition or bonding material layer is heated at 240°C or higher in an inert atmosphere such as nitrogen to form a bonding layer that bonds the first member and the second member. Although the upper limit of the heating temperature is not particularly limited, it is, for example, 300° C. or less. The heating time is preferably 60 to 120 minutes, more preferably 30 to 90 minutes, even more preferably 5 to 60 minutes.

For heat treatment, hot plate, hot air dryer, hot air heating furnace, nitrogen dryer, infrared dryer, infrared heating furnace, far infrared heating furnace, microwave heating device, laser heating device, electromagnetic heating device, heater heating Apparatus, steam-heated furnaces, etc. can be used. For the heating and pressurizing treatment, a hot plate press device or the like may be used, or the above-mentioned heating treatment may be performed while pressurizing.

When the bonding material composition or bonding material layer is heated, the flux first begins to remove the Cu ₂ O layer covering the Cu of the core (C1) of the first metal particles (P1). When the melting point of Sn is reached, the Sn covering the Cu of the core (C2) of the second metal particle (P2) or the solder containing Sn melts, and the surface of the Cu of the core (C2) and the first metal particle ( It wets and spreads on the Cu surface of the core (C1) of P1). Then, Sn reacts with Cu of the core (C2) to form Cu ₆ Sn ₅ , which is an intermediate compound of Cu—Sn. In addition, Sn and Cu react on the surface of the core (C1) to form Cu ₆ Sn ₅ , which is an intermediate compound of Cu—Sn. Furthermore, by continuing the heating, Cu ₃ Sn is formed because Cu is supplied to the Cu ₆ Sn ₅ , and a bonding layer is formed. The bonding layer preferably has a thickness of 10 to 300 μm.

As described above, a joined body in which the first member and the second member are joined by the joining layer is manufactured.

Here, the Cu of the core (C1) is covered with a Cu ₂ O layer, and the flux removes the Cu ₂ O layer during heating, while the Sn melts, so that the Cu and Sn of the core (C2) Since the reaction starts first, Cu ₃ Sn is surely formed inside the second metal particles (P2), so most of the second metal particles (P2) become Cu ₃ Sn particles, but some Cu may remain inside the particles.

In addition, the Cu of the core (C1) is covered with a Cu ₂ O layer, and while the flux removes the Cu ₂ O layer during heating, Sn melts, so that the melted Sn becomes the first metal particles ( When the Cu ₂ O layer is removed, Sn reacts with Cu of the core (C1), so that Cu ₃ Sn is uniformly formed on the surface of the core (C1). The first metal particles (P1) preferably have a larger average particle size than the second metal particles (P2), and the reaction between Sn and Cu in the core (C1) Cu remains inside the core (C1) because the reaction starts later than the reaction inside.

As a result, the bonding layer formed by heating the bonding material composition or bonding material layer has a network structure in which Cu particles are bonded by a compound of Cu and Sn. Therefore, the obtained bonding layer has extremely high shear strength, heat resistance, electrical conductivity and heat dissipation.

Next, examples of the present invention will be described, but the present invention is not limited to these examples.

<raw materials>
[First metal particles (P1)]
(P1) A: Cu particles (MA series, manufactured by Mitsui Mining & Smelting Co., Ltd.) were heated in an oven at 200° C. for 1 hour to obtain metal particles in which the Cu particles were coated with a Cu ₂ O layer. The average particle size (D50) was 5 µm and the oxidation degree H was 0.05. The oxidation degree H is an X-ray diffractometer (X'PertPRO (trade name), manufactured by Malvern Panalytical Co., Ltd.), and the diffraction intensity H1 of the Cu (111) plane and the diffraction intensity of the Cu ₂ O (111) plane The intensity H2 was measured and obtained from H=H2/(H1+H2). The average particle size (D50) of the metal particles was measured with a laser diffractometer (SALD-3100 (trade name), manufactured by Shimadzu Corporation).

(P1) B: Cu particles (MA series, manufactured by Mitsui Mining & Smelting Co., Ltd.) were heated in an oven at 180° C. for 3 hours to obtain metal particles in which the Cu particles were coated with a Cu ₂ O layer. The average particle size (D50) was 5 µm, and the degree of oxidation H was 0.3. The degree of oxidation H and average particle size (D50) were measured in the same manner as in (P1)A.

(P1) C: Cu particles (MA series, manufactured by Mitsui Kinzoku Mining Co., Ltd.) were heated in an oven at 300° C. for 40 minutes to obtain metal particles in which the Cu particles were coated with a Cu2O layer. The average particle size (D50) was 5 μm and the degree of oxidation H was 0.5. The degree of oxidation H and average particle size (D50) were measured in the same manner as in (P1)A.

(P1) D: Cu particles (MA series, manufactured by Mitsui Mining & Smelting Co., Ltd.) were used. The average particle size (D50) was 5 μm, and the oxidation degree H was 0. The average particle size (D50) was measured in the same manner as in (P1)A.

(P1) E: Cu particles (MA series, manufactured by Mitsui Mining & Smelting Co., Ltd.) were heated in an oven at 200° C. for 1 hour to obtain metal particles in which the Cu particles were coated with a Cu ₂ O layer. The average particle size (D50) was 10 μm, and the degree of oxidation H was 0.05. The degree of oxidation H and average particle size (D50) were measured in the same manner as in (P1)A.

(P1) F: Cu particles (1030Y series, manufactured by Mitsui Kinzoku Mining Co., Ltd.) were heated in an oven at 180° C. for 4 hours to obtain metal particles in which the Cu particles were coated with a Cu ₂ O layer. The average particle size (D50) was 0.5 μm, and the degree of oxidation H was 0.1. The degree of oxidation H and average particle size (D50) were measured in the same manner as in (P1)A.

(P1) G: Cu particles (MA series, manufactured by Mitsui Mining & Smelting Co., Ltd.) were heated in an oven at 200° C. for 40 hours to obtain metal particles in which the Cu particles were coated with a Cu ₂ O layer. The average particle size (D50) was 50 µm and the degree of oxidation H was 0.05. The degree of oxidation H and average particle size (D50) were measured in the same manner as in (P1)A.

(P1) H: Ag particles (SP series, manufactured by Mitsui Mining & Smelting Co., Ltd.) were used. The average particle size (D50) was 5 μm, and the oxidation degree H was 0. The average particle size (D50) was measured in the same manner as in (P1)A.

(P1) I: Cu particles (MA series, manufactured by Mitsui Mining & Smelting Co., Ltd.) were heated in an oven at 200° C. for 30 hours to obtain metal particles in which the Cu particles were coated with a Cu ₂ O layer. The average particle size (D50) was 25 μm and the oxidation degree H was 0.05. The degree of oxidation H and average particle size (D50) were measured in the same manner as in (P1)A.

(P1) J: Cu particles (MA series, manufactured by Mitsui Mining & Smelting Co., Ltd.) were heated in an oven at 170° C. for 4 hours to obtain metal particles in which the Cu particles were coated with a Cu ₂ O layer. The average particle size (D50) was 5 µm and the degree of oxidation H was 0.31. The degree of oxidation H and average particle size (D50) were measured in the same manner as in (P1)A.

(P1) K: Cu particles (1030Y series, manufactured by Mitsui Kinzoku Mining Co., Ltd.) were heated in an oven at 170°C for 3 hours to obtain metal particles in which the Cu particles were coated with a Cu ₂ O layer. The average particle size (D50) was 0.5 μm, and the oxidation degree H was 0.07. The degree of oxidation H and average particle size (D50) were measured in the same manner as in (P1)A.

[Second metal particles (P2)]
(P2) A: Particles in which Cu particles were coated with Sn (1050Y series, manufactured by Mitsui Mining & Smelting Co., Ltd.) were used. The average particle size (D50) was 2 μm. The average particle size (D50) was measured in the same manner as in (P1)A.

(P2) B: Particles in which Cu particles were coated with Sn (1050Y series, manufactured by Mitsui Mining & Smelting Co., Ltd.) were used. The average particle size (D50) was 5 μm. The average particle size (D50) was measured in the same manner as in (P1)A.

(P2) C: Cu particles coated with SnNiCu (developed product, manufactured by Kyokuto Boeki Co., Ltd.) were used. The average particle size (D50) was 2 μm. The average particle size (D50) was measured in the same manner as in (P1)A.

(P2) D: Particles in which Cu particles were coated with SnNiCu (developed product, manufactured by Kyokuto Boeki Co., Ltd.) were used. The average particle size (D50) was 5 μm. The average particle size (D50) was measured in the same manner as in (P1)A.

(P2) E: Sn-coated Cu particles (1050Y series, manufactured by Mitsui Mining & Smelting Co., Ltd.) were used. The average particle size (D50) was 0.5 μm. The average particle size (D50) was measured in the same manner as in (P1)A.

(P2) F: Sn-coated Cu particles (1050Y series, manufactured by Mitsui Mining & Smelting Co., Ltd.) were used. The average particle size (D50) was 20 μm. The average particle size (D50) was measured in the same manner as in (P1)A.

(P2) G: Cu particles coated with In (developed product, manufactured by Kyokuto Boeki Co., Ltd.) were used. The average particle size (D50) was 2 μm. The average particle size (D50) was measured in the same manner as in (P1)A.

(P2) H: Sn particles (STC series, manufactured by Mitsui Mining & Smelting Co., Ltd.) were used. The average particle size (D50) was 2 μm. The average particle size (D50) was measured in the same manner as in (P1)A.

(P2) I: Sn-coated Cu particles (1050Y series, manufactured by Mitsui Mining & Smelting Co., Ltd.) were used. The average particle size (D50) was 12 μm. The average particle size (D50) was measured in the same manner as in (P1)A.

[Third metal particles (P3)]
(P3) A: Sn particles (ST series, manufactured by Mitsui Mining & Smelting Co., Ltd.) were used. The average particle size (D50) was 5 μm. The average particle size (D50) was measured in the same manner as in (P1)A.

(P3) B: SnNiCu particles (STC series, manufactured by Mitsui Mining & Smelting Co., Ltd.) were used. The average particle size (D50) was 5 μm. The average particle size (D50) was measured in the same manner as in (P1)A.

[Thermosetting resin]
Thermosetting resin A: Bismaleimide resin (BMI-3000 (trade name), DESIGNER MOLECULES INC., number average molecular weight 3000) and polymerization initiator (Nofmer BC (trade name), 2,3-dimethyl-2,3- Diphenylbutane (manufactured by NOF Corporation) was mixed at a mass ratio of 100:5 to obtain a maleimide resin.

[flux]
Flux A: organic sulfides (MPSMA (registered trademark), bis(4-methacryloylthiophenyl) sulfide, manufactured by Sumitomo Seika Co., Ltd.)
Flux B: Phosphine-based (DPPST, p-styryldiphenylphosphine, manufactured by Hokko Sangyo Co., Ltd.)

<Production of bonding material composition (bonding paste)>
(Example 1)
First, (P1) A is immersed in a solution of flux A and stirred for 120 minutes at an output of 50 W and 3000 rpm using an ultrasonic device (NS-56 (trade name), manufactured by Microtech Nition Co., Ltd.). , the flux was coordinated to the surface of the first metal particles (P1). Flux content was determined using FT-IR (Fourier transform infrared spectroscopy) measurements. Next, (P1)A and (P2)A modified with the above fluxes and cyclopentanone (manufactured by Kanto Kagaku Co., Ltd.) as a solvent were mixed and stirred in the mixing ratios shown in Tables 1 to 3 to prepare Example 1. A bonding material composition, that is, a bonding paste, was obtained.

(Examples 2-4, 10-20, Comparative Examples 1-5)
In the same manner as in Example 1, bonding material compositions, that is, bonding pastes, according to Examples 2 to 4, 10 to 20, and Comparative Examples 1 to 5 were obtained with the raw materials and blending ratios shown in Tables 1 and 2. For Comparative Example 5, all raw materials were kneaded without modifying the surfaces of the first metal particles with flux.

(Example 5)
First, (P1) A is immersed in a solution of flux B and stirred for 120 minutes at an output of 50 W and 3000 rpm using an ultrasonic device (NS-56 (trade name), manufactured by Microtech Nition Co., Ltd.). , the flux was coordinated to the surface of the first metal particles (P1). After that, in the same manner as in Example 1, a bonding material composition, that is, a bonding paste, according to Example 5 was obtained with the raw materials and blending ratios shown in Tables 1 and 2.

(Example 6)
In the same manner as in Example 5, a bonding material composition, ie, a bonding paste, according to Example 6 was obtained with the raw materials and blending ratios shown in Tables 1 and 2.

<Preparation of bonding material layer>
(Example 7)
First, (P1) A is immersed in a solution of flux A and stirred for 120 minutes at an output of 50 W and 3000 rpm using an ultrasonic device (NS-56 (trade name), manufactured by Microtech Nition Co., Ltd.). , the flux was coordinated to the surface of the first metal particles (P1). Flux content was determined using FT-IR (Fourier transform infrared spectroscopy) measurements. Next, (P1) A and (P2) A modified with the above flux, thermosetting resin A, and cyclopentanone (manufactured by Kanto Kagaku Co., Ltd.) as a solvent were mixed in the mixing ratios shown in Tables 1 and 2, The stirred product was coated on a Teflon (registered trademark) sheet so that the film thickness after drying was 100 μm, dried at 100 ° C. for 5 minutes, peeled off from the Teflon (registered trademark) sheet, and applied to Example 7. Such a bonding material layer was obtained.

(Examples 8 and 9)
Bonding material layers according to Examples 8 and 9 were obtained in the same manner as in Example 7, using the raw materials and mixing ratios shown in Tables 1 and 2.

<Evaluation>
The properties of the bonding material compositions (bonding pastes) and bonding material layers according to Examples and Comparative Examples obtained as described above were evaluated as follows. Table 3 shows the results.

(Examples 1 to 6, 10 to 20, Comparative Examples 1 to 5)
[Share strength]
50 mg of the bonding material composition (bonding paste) according to the above examples and comparative examples was applied onto a Cu lead frame. A chip is prepared by dicing an Au-plated Si wafer into 3 mm squares, and the chip is placed on the applied bonding material composition (bonding paste) so that the Au plating is in contact with the bonding material composition (bonding paste). , and pressed lightly with tweezers to adhere to the bonding material composition (bonding paste) to obtain a laminate. This laminate was baked at 280° C. for 15 minutes in a nitrogen atmosphere to obtain a sample for measurement.

For the obtained measurement sample, using a die shear measuring machine (manufactured by Nordson Advanced Technologies Co., Ltd. universal bond tester series 4000), the scratching tool of the bond tester was made to collide with the side surface of the chip of the measurement sample at 100 μm / s, The stress at which the chip/lead frame bond failed was measured as the shear strength at 260°C. If the shear strength is 10.0 MPa or more, it is evaluated as "Good", if it is less than 10.0 MPa and 3.0 or more, it is evaluated as "△", and if it is less than 3.0 MPa, it is evaluated as "X" did.

[Heat-resistant]
Next, a measurement sample obtained in the same manner as the above measurement sample is subjected to a thermal shock test (TCT), held at a temperature of -65 ° C. for 10 minutes, and then held at a temperature of 175 ° C. for 10 minutes. The treatment process was defined as one cycle, and 500 cycles of this treatment were performed. For the measurement sample after this treatment, the shear strength after TCT was measured in the same manner as for the shear strength before TCT. It means that the higher the shear strength after TCT, the better the heat resistance. If the shear strength after TCT is 7.0 MPa or more, it is regarded as a good product. ” was evaluated.

[Conductivity]
100 mg of the bonding material composition according to the examples and comparative examples was applied onto a glass substrate and baked at 280° C. for 15 minutes to obtain a measurement sample. For this measurement sample, the resistance value was measured by the four-probe method in accordance with JIS-K7194-1994, and the volume resistivity was calculated. Loresta GX manufactured by Mitsubishi Chemical Analytech Co., Ltd. was used to measure the resistance value. The reciprocal of the volume resistivity is conductivity, and the smaller the volume resistivity, the better the conductivity.
In this example, a product with a volume resistivity of less than 1.0×10 ⁻⁵ Ω·cm is regarded as a good product, and a product with a volume resistivity of 1.0×10 ⁻⁵ Ω·cm or more and 5.0×10 ⁻⁵ Ω·cm cm or less was evaluated as an acceptable product, and those exceeding 5.0×10 ⁻⁵ Ω·cm were evaluated as a defective product with an “X”.
[Heat dissipation]
Thermal conductivity is determined by expressing volume resistivity as IACS conductivity. The volume resistivity of 1.724 × 10 ^-6 Ω cm of annealed standard copper is 100IACS%, and the volume resistivity is expressed as a ratio, and the thermal conductivity of 360W when copper is 100IACS% is divided by the ratio. , the thermal conductivity was calculated based on copper. In addition, thermal conductivity means that it is excellent in heat dissipation, so that it is large.
In this example, those with a thermal conductivity of 70 W/m·K or more are regarded as excellent products, and those with a thermal conductivity of less than 70 W/m·K and 40 W/m·K or more are regarded as good products, and 40 W/m・Those with less than K of 17 W/m·K or more were evaluated as “acceptable”, and those with less than 17 W/m·K were evaluated as “poor”.

(Examples 7-9)
[Share strength]
The bonding material layers according to Examples 7 to 9 were placed on a Cu lead frame. A chip was prepared by dicing an Au-plated Si wafer into 3 mm squares, and the chip was placed on the bonding material layer so that the Au plating was in contact with the bonding material layer to obtain a laminate. This laminate was baked at 280° C. for 15 minutes in a nitrogen atmosphere to obtain a sample for measurement.

For the obtained measurement samples, the shear strength was measured by the same method as the shear strength described above, and the shear strength was evaluated by the same method.

[Heat-resistant]
Next, for the measurement sample obtained in the same manner as the above measurement sample, the shear strength after TCT was measured by the same method as the above-described shear strength after TCT, and the heat resistance was evaluated by the same method. Ta.

[Conductivity]
The bonding material layers according to Examples 7 to 9 were baked at 280° C. for 15 minutes to obtain measurement samples. Regarding this measurement sample, the volume resistivity was calculated by the same method as described above, and the electrical conductivity was evaluated by the same method.

[Heat dissipation]
For this measurement sample, the thermal conductivity was calculated by the same method as described above, and the heat dissipation property was evaluated by the same method.

The bonding material compositions (bonding pastes) and bonding material layers according to Examples 1 to 20 were obtained by using metal particles in which Cu particles were coated with a Cu ₂ O layer and metal particles in which Cu particles were coated with Sn or SnNiCu. Therefore, the diffusion is suppressed until the Cu ₂ O layer is reduced, so the reaction proceeds slowly and the reaction is uniform as a whole. result.

In the bonding material composition according to Comparative Example 1, Cu particles not covered with a Cu ₂ O layer were used as the first metal particles (P1). The diffusion reaction is not formed uniformly, and while a large amount of Cu ₃ Sn is formed in the region where the reaction has sufficiently progressed, there are portions where the reaction is insufficient or unreacted, and a network structure with Cu particles as the core is obtained. However, the heat resistance, electrical conductivity, and heat dissipation were inferior.

Since the bonding material composition according to Comparative Example 2 used Ag particles having a good oxidation state as the first metal particles (P1), the Ag ₃ Sn and Cu ₃ Sn regions were separated by reacting with Sn. structure, resulting in poor heat resistance and heat dissipation.

In the bonding material composition according to Comparative Example 3, since indium-plated Cu particles were used as the second metal particles (P2), indium melts at a low temperature but has poor diffusion reactivity with Cu. Only the CuIn compound was produced, resulting in poor heat resistance, electrical conductivity, and heat dissipation.

In the bonding material composition according to Comparative Example 4, pure Sn particles were used as the second metal particles ( _P2 ). reacted with Au on the back surface of the Si chip, resulting in poor heat resistance due to insufficient reaction with Cu particles.

Since the bonding material composition according to Comparative Example 5 did not use flux, the reduction of Cu ₂ O did not progress, Sn could not react with the Cu core, and a structure of Cu ₃ Sn was not formed. , the results were inferior in all of heat resistance, electrical conductivity, and heat dissipation.

Claims (21)

1. Including metal particles (P) including first metal particles (P1) and second metal particles (P2) and flux,
   The first metal particles (P1) are composed of a core (C1) made of Cu and a Cu ₂ O layer covering the core (C1),
   A bonding material composition, wherein the second metal particles (P2) are composed of a core (C2) made of Cu and Sn or a solder containing Sn coating the core (C2).
2. The first metal particles (P1) have an average particle size of 1 to 20 μm,
   The bonding material composition according to claim 1, wherein the second metal particles (P2) have an average particle size of 1 to 10 µm.
3. The ratio of Sn in the Sn or Sn-containing solder covering the core (C2) is 55 to 65 mass% with respect to the total amount of 100% by mass of the Cu of the core (C1) and the Cu of the core (C2). %.
4. When the diffraction intensity of the Cu (111) plane of the first metal particles (P1) measured by X-ray diffraction is H1, and the diffraction intensity of the Cu ₂ O (111) plane is H2, the following formula 1 The bonding material according to any one of claims 1 to 3, wherein the oxidation degree H of the first metal particles (P1) represented by is 0.05 to 0.3. Composition.
   H=H2/(H1+H2) [Formula 1]
5. The metal particles (P) further include third metal particles (P3),
   The bonding material composition according to any one of claims 1 to 4, wherein the third metal particles (P3) are Sn particles or Sn-containing solder particles.
6. Sn in a solder containing Sn or Sn covering the core (C2), and the Sn particles or Sn The bonding material composition according to claim 5, wherein the proportion of Sn in the solder particles containing is 55 to 65% by mass.
7. The bonding material composition according to any one of claims 1 to 6, characterized in that the flux has reducing properties and does not contain water in the reaction product.
8. 8. The flux according to any one of claims 1 to 7, wherein the flux contains at least one of phosphines represented by the following general formula (1) and sulfides represented by the following general formula (2). The bonding material composition described.
   However, in the following general formulas (1) and (2), each R independently represents an organic group, and each R may be the same or different.
   

   
9. The bonding material according to any one of claims 1 to 8, wherein the content of the flux is 0.05 to 0.5% by mass with respect to the metal particles (P). Composition.
10. The bonding material composition according to any one of claims 1 to 9, wherein the content of the metal particles (P) is 80 to 95% by mass with respect to the total amount of the bonding material composition. .
11. forming a bonding layer that bonds the first member and the second member by heating at 240° C. or higher;
    The bonding material composition according to any one of claims 1 to 10, wherein the bonding layer has a network structure in which Cu particles are bonded by a compound of Cu and Sn.
12. The bonding material composition according to any one of claims 1 to 11, characterized by containing a thermosetting resin.
13. 13. The method for producing the bonding material composition according to any one of claims 1 to 12, wherein the first metal particles (P1) and the second metal particles (P2) are mixed and stirred. A method for producing a bonding material composition, comprising:
14. A bonding film having a bonding material layer,
    A bonding film, wherein the bonding material layer is formed using the bonding material composition according to any one of claims 1 to 12.
15. The bonding film according to claim 14, wherein the bonding material layer has a thickness of 10 to 100 µm.
16. A method for manufacturing a joined body in which a first member and a second member are joined by a joining layer using the joining material composition according to any one of claims 1 to 12,
    By interposing the bonding material composition between the first member and the second member and heating at 240° C. or higher, the flux converts the Cu ₂ O of the first metal particles (P1) into removing the layer, the Sn or the Sn-containing solder of the second metal particles (P2) melts and reacts with the Cu of the core (C1) and the Cu of the core (C2); A method for manufacturing a bonded body, wherein the bonding layer having a network structure in which Cu particles are bonded by a compound of Cu and Sn is formed.
17. 16. A method for producing a joined body in which a first member and a second member are joined by a joining layer using the joining film according to claim 14 or 15, the method comprising:
    By interposing the bonding material layer between the first member and the second member and heating at 240° C. or higher, the flux forms the Cu ₂ O layer of the first metal particles (P1). is removed, the Sn or the Sn-containing solder of the second metal particles (P2) melts, reacts with the Cu of the core (C1) and the Cu of the core (C2), and Cu A method for producing a joined body, wherein the joining layer having a network structure in which particles are joined by a compound of Cu and Sn is formed.
18. A bonded body obtained by bonding a first member and a second member with a bonding layer using the bonding material composition according to any one of claims 1 to 12,
    A bonded body, wherein the bonding layer is formed by heating the bonding material composition at 240° C. or higher.
19. A bonded body obtained by bonding a first member and a second member with a bonding layer using the bonded film according to claim 14 or 15,
    A bonded body, wherein the bonding layer is formed by heating the bonding material layer at 240° C. or higher.
20. The joined body according to claim 18 or 19, wherein the joining layer has a network structure in which Cu particles are joined by a compound of Cu and Sn.
21. The joined body according to any one of claims 18 to 20, wherein the joining layer has a thickness of 10 to 300 µm.